End of valve motion detection for a spool control valve

Abstract

A fuel injector system ( 10 ) includes a piezoelectric sensor ( 52 ) mounted along a spool valve axis ( 18 ) of the injector body ( 12 ). The piezoelectric sensor ( 52 ) is mounted within a spool valve stop ( 41 ). As the spool valve ( 16 ) reaches the stop ( 41 ), the piezoelectric sensor ( 52 ) identifies the force exerted thereupon and transmits the generated signal to the controller ( 44 ). Through communication with piezoelectric sensor ( 52 ) the controller determines when the spool valve ( 16 ) has reached a predetermined position.

1. A method of injecting fuel comprising the steps of:
 (1) providing a fuel to a spool valve movable between a first and a second coil such that the spool valve selectively provides fuel flow to a fuel injector when the spool valve is located in a first position and prevents fuel flow to the fuel injector in a second position;  
 (2) locating a piezoelectric sensor adjacent the spool valve;  
 (3) measuring a signal generated by the piezoelectric sensor;  
 (4) determining a predetermined position of the spool valve in response to said step (3); and  
 (5) locating a measurement window within a time period defined between a first command signal and a second command signal.  
 
   
   
     2. A method as recited in  claim 1 , wherein said step (3) is performed within a predetermined timing window. 
   
   
     3. A method as recited in  claim 1 , wherein the signal is a voltage. 
   
   
     4. A method as recited in  claim 1 , further comprising the step of locating the piezoelectric sensor within a stop adjacent the spool valve. 
   
   
     5. A method as recited in  claim 1 , further comprising the step of: identifying a signal from the piezoelectric sensor in response to contact between the spool valve and the piezoelectric sensor. 
   
   
     6. A method as recited in  claim 5 , further comprising the step of: determining whether the signal from the piezoelectric sensor is within the measurement window. 
   
   
     7. A method as recited in  claim 1 , wherein said step (2) comprises
 moving the spool valve along a spool valve axis to selectively contact the piezoelectric sensor.